The oil and gas industry expends sizable sums to design cutting tools, such as downhole drill bits including roller cone rock bits and fixed cutter bits, which have relatively long service lives, with relatively infrequent failure. In particular, considerable sums are expended in the design and manufacture of roller cone rock bits and fixed cutter bits in a manner that minimizes the opportunity for catastrophic drill bit failure during drilling operations. The loss of a roller cone or a polycrystalline diamond compact (PDC) from a fixed cutter bit during drilling operations can impede the drilling operations and, at worst, necessitate rather expensive fishing operations. If the fishing operations fail, so-called “sidetrack drilling” operations must be performed in order to drill around the portion of the wellbore containing the lost roller cones or PDC cutters. Typically, during drilling operations, bits are pulled and replaced prematurely with new bits even though significant service could still be obtained from the replaced bit. Such premature replacements of downhole drill bits are expensive, since each trip out of the well prolongs the overall drilling activity, and consumes considerable manpower, but are nevertheless done in order to avoid the far more disruptive and expensive process of, at best, pulling the drill string and replacing the bit upon detection of failure or, at worst, having to undertake fishing and sidetrack drilling operations necessary if one or more cones or compacts are lost due to bit failure.
With the ever-increasing need for downhole drilling system dynamic data, a number of “subs” (i.e., a sub-assembly including sensors incorporated into the drill string above the drill bit and used to collect data relating to drilling parameters) have been designed and installed in drill strings. Unfortunately, these subs cannot provide actual data for what is happening operationally at the bit due to their remote physical placement above the bit itself.
Data acquisition is conventionally accomplished by mounting a sub in the bottom-hole assembly (BHA) several feet to tens of feet away from the bit. Data gathered from a sub this far away from the bit may not accurately reflect what is happening directly at the bit while drilling occurs. Often, this lack of data leads to conjecture as to what may have caused a bit to fail or why a bit performed so well, with no directly relevant facts or data to correlate to the performance of the bit.
There is a need for a drill bit equipped to measure and report data that is related to performance and condition of the drill bit during operation. Such a drill bit may extend useful bit life in a given wellbore, enable re-use of a bit in multiple drilling operations and provide an ability to develop drill bit performance data on existing drill bits, which may be used for developing future improvements to drill bits.